Vacuum may be consumed by various devices in a vehicle. For example, vacuum may be utilized in brake assist or a power braking system to multiply force that is applied by a vehicle operator to a brake pedal. The multiplied force may be applied to a master brake cylinder to provide vehicle braking. The brake assist may allow the vehicle operator to apply the brakes with less effort and more comfort relative to unassisted braking. In some implementations, at least some vacuum for brake assist may be provided by an electrically driven vacuum pump (EVP).
In one example, an electrically driven vacuum pump is operable to pump air from a boosted engine to provide vacuum for a brake booster. In particular, during operation of the electrically driven vacuum pump, air is pumped from the brake booster, through the electrically driven vacuum pump, and exhausted to the intake manifold downstream of the turbocharger.
However, the inventors herein have recognized potential issues with such an approach. For example, since air is merely circulated to and from the intake manifold downstream of the turbocharger, a differential pressure and correspondingly the air flow rate of the electrically driven vacuum pump is low. Accordingly, the electrically driven vacuum pump may be operated more frequently to meet the vacuum consumption demands of the brake booster. This may result in a shorter operational lifespan of the electrically driven vacuum pump. Moreover, the low air flow rate may result in a slow rate of vacuum production when the electrically driven vacuum pump is turned on.
Thus, in one example, some of the above issues may be addressed by a system for supplying vacuum to a vacuum consumption device of a vehicle. The system includes an electrically driven vacuum pump selectively routing air to an air intake system upstream of a turbocharger compressor and downstream of a throttle into the intake manifold.
By selectively routing air exhausted from the electrically driven vacuum pump upstream of the turbocharger or into the intake manifold, air may be exhausted to a lowest available pressure. Accordingly, the pressure differential and correspondingly the air flow rate of the electrically driven vacuum pump may be increased relative to a configuration that merely routes air to the intake manifold downstream of the turbocharger. In this way, the electrically driven vacuum pump may be operated less frequently, and the operational lifespan of the electrically driven vacuum pump may be increased relative to the configuration that merely routes air to the intake manifold downstream of the turbocharger.
Furthermore, the increase of the air flow rate reduces brake vacuum recovery time. In this way, a suitable amount of vacuum may be provided for repeated brake actuations. Moreover, the increased flow rate generates a greater amount of vacuum that may facilitate the downsizing of the electrically driven vacuum pump by a pump size. In this way, a cost and weight reduction of the vehicle may be achieved.
It will be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description, which follows. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined by the claims that follow the detailed description. Further, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.